1. Field of the Invention
This invention relates to infinitely variable ratio transmission apparatus, and more particularly to such apparatus employing permanent magnets for transmitting energy and varying the amount of energy transmitted. It is contemplated that the present invention is of particular utility in personal passenger transportation vehicles having energy accumulating flywheels for supplying certain portions of the energy for propelling the vehicle, although its applicability is not intended to be absolutely limited in this manner.
2. Brief Description of the Prior Art
As is known in the art, infinitely variable ratio transmissions are utilized to transfer variable energy or torque without regard to the speed of rotation of the input and output elements and to effectively separate the input from the output in an infinite number of torque or power transmitting ratios. In general infinitely variable ratio transmissions are utilized where the input speeds vary greatly with respect to the output speeds. Typical examples of infinitely variable ratio transmissions are motor-generator units, variable capacity fluid drive or pumping systems, and variable diameter sheaves in pulley belt drive systems. The latter belt drive system, however, is not strictly an infinitely variable ratio arrangement, since the ratios are limited by the finite diameter of the variable sheaves.
Infinitely variable ratio transmissions have been utilized in various types of vehicles, although each type of transmission involves certain limitations when used. Motor generator units of sufficient power and energy transmitting capability for transportation vehicles are very expensive, of relatively large size and are generally very heavy. The motor-generator unit has very good variable torque transmitting characteristics, and for this reason is usually utilized in high power situations where weight, size and expense are not critical, such as in railway locomotives. However, to utilize a motor-generator unit in a personal passenger vehicle is prohibitive because of the size, weight and expense of the motor-generator unit. The size of the motor-generator unit increases the size of the vehicle or decreases the space available for use in the vehicle. Fuel is consumed just in propelling the relatively heavy motor-generator unit, which significantly decreases transportation economy.
Variable capacity fluid drive transmission systems, such as hydrostatic transmissions, have relatively good power handling capabilities. Hydrostatic transmissions employ relatively complicated variable capacity pumps and hydraulic motors which tend toward increasing their cost. Further, the efficiency of hydrostatic transmissions is typically poor and these transmissions usually operate at high noise levels.
Variable sheave pulley belt systems have limited power handling capability due to the structural strength of the belts and the apparatus controlling the diameter of the variable sheave. In general, the variable sheave pulley belt systems are not as versatile as true infinitely variable ratio transmission, since the ratio of the belt system is limited by the finite diameter of the pulleys. To overcome this, it is typical that a plurality of variable sheave pulley belt systems are operatively connected together to achieve an extended range of variable ratios or steps. This arrangement however, additionally requires the use of a clutch for most typical situations. When a plurality of such systems are utilized together they consume a relatively large amount of space, the control means linking each unit together may become relatively complex, and the time to effect significant changes in ratios is usually very long.
When utilized in a personal passenger transportation vehicle the infinitely variable ratio transmission should obtain certain requirements. The transmission should be relatively small and light in weight to avoid consuming excessive space and detracting from economy of vehicle operation. The transmission should be relatively dependable in operation and provide a long lifetime of use. The transmission should be as efficient as possible in transferring the highest proportion of input energy to its output, and should have a relatively high energy transmitting or power handling capability to propel an average sized passenger vehicle. The transmission should also have the capability of absorbing energy supplied from the vehicle, such as during braking or stopping thus acting as a fail-safe vehicle brake. Since it is possible with true infinitely variable ratio transmission to avoid use of a clutch, the transmission should be of a configuration which advantageously and inherently provides the function of a clutch. When an engine and energy accumulating flywheel are utilized as a vehicle power plant an infinitely variable ratio transmission is usually required for delivering energy from the flywheel to propel the vehicle, since the flywheel will typically decrease in rotational speed as energy is supplied to the driving mechanism of the vehicle. The infinitely variable ratio transmission can increase the speed of its output shaft as its input shaft slows down, thus allowing the vehicle speed to be advantageously increased or controlled independently of the flywheel speed.
A problem concerning dynamic braking is also present in vehicles utilizing energy accumulating flywheels. In a situation where the flywheel has accumulated maximum energy and is rotating at approximately its maximum safe speed, slowing the vehicle could add energy to the flywheel by increasing its rotational speed. The increased rotational speed may cause the flywheel to shatter or disintegrate with potentially dangerous results. To overcome this situation with a typical infinitely variable ratio transmission requires governors and auxiliary brakes on the flywheel or a sophisticated tachometer control to bypass the energy from the flywheel, all of which are relatively expensive.
A fuller appreciation for the use of the present invention is a vehicle propelled by an engine and flywheel energy accumulator, and the requirements of an infinitely variable ratio transmission in a vehicle can be obtained from Low Energy Consumption Vehicle Powered by Thermal Engine, Ser. No. 786,547, and Flywheel Energy Accumulator, Ser. No. 786,544, filed on the filing date herein by the same inventor.
Many of the foregoing requirements and limitations have applicability in situations where the transmission apparatus is not used with a vehicle. For example eddy current drives are sometimes utilized in a variety of torque transmitting applications. Eddy current drives are usually complicated since electrical coils and electrical conducting circuits are involved. Eddy current drives also require a source of electricity for operation. It should be appreciated that the present invention may be advantageously used as an alternative to known transmission apparatus where the application involves many of the previously discussed requirements and limitations.